... this posting was sent last Monday but apparently hadn't made it through the reflector - hopefully still interesting.
Regards
Markus, DF6NM
Thema: TA and NPG on Colour DF
Datum: 17.10.2005 19:36:59 Westeuropäische Sommerzeit
Von: Markus Vester
An: [email protected]
Dear LF Group,
last night, I found a strong and isolated peak from XKO around 3:20, and more traces from XGJ, XES, XKO and NA around 5:30. The grabber snapshot is at
http://members.aol.com/df6nm2/TA_17Oct05.gif (273kB).
A screenshot of the NPG pair during its "good nights" on Oct. 15 and 16th is on
http://members.aol.com/df6nm2/NPG_15-16Oct05.gif (52kB).
Besides their sheer strength, one remarkable thing about these traces is the fairly uniform colour on the direction finder over the night. Quite unlike medium-range traces like SXV or the unid carrier near 137689.5 which sometimes show up to 360° colour changes around the fading minima. I believe these directional errors are probably produced by two mechanisms:
- in a fade caused by two ore more azimutally oblique paths, the angle of the resulting magnetic field vector can be offset from that of either path by a large degree;
- for steep incidence, the horizontal conductors of the loops receive field components with apparent directions depending on the polarization rather than actual azimuth, and which may have been altered by Faraday rotation in the ionosphere. I noted in the past that some European stations tend to display more variation than others, and have attributed this to either more pronounced skywave radiation by relatively large horizontal TX antenna current components, or to groundwave blocking by mountainous terrain. A low-angle DX signal would naturally suffer less from this effect.
73 from Nuernberg
Markus, DF6NM
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